I had Rentokil come out to my house, the guy was very helpful, gave me loads of suggestions on how to keep the mice out. Clearly he was trying to sell me their services, but as I live rurally and mice just come with the location I didn't feel the need to start killing mice outside my house.
Based on his advice I mouse proofed the living area of my house and set some traps again. Result since then 1 or 2 mice caught each year ( as opposed to double digits). The advice came for free and he hasn't been bothering me since to buy their services.
As I am now starting the building work on my attic I may have to review the situation again, as there are clearly a lot of mice in the attic that didn't bother me , but clearly will bother me when I have bedrooms there